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Gao Y, Du P. miR-4529-3p Promotes the Progression of Retinoblastoma by Inhibiting RB1 Expression and Activating the ERK Signaling Pathway. Mol Biotechnol 2024; 66:102-111. [PMID: 37041423 DOI: 10.1007/s12033-023-00738-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2022] [Accepted: 03/26/2023] [Indexed: 04/13/2023]
Abstract
Retinoblastoma (RB) is a malignant ocular cancer that affects children. Several microRNAs (miRNAs) have been implicated in RB regulation. The present study aimed to investigate the role of miR-4529-3p in RB pathogenesis. Scratch, Transwell, and Cell Counting Kit (CCK)-8 assays were conducted to assess the migratory, invasive, and proliferative abilities of RB cells. The expression levels of miR-4529-3p, RB1, and ERK pathway-related proteins were analyzed using western blotting and real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). Target relationships were verified using dual-luciferase reporter experiments. A murine RB model was developed to analyze the effects of miR-4529-3p on RB tumor growth in vivo. Our experiments revealed high levels of miR-4529-3p and low levels of RB1 in RB tissues. Functional analyses revealed that the migratory, invasive, and proliferative abilities of RB cells were repressed by miR-4529-3p inhibition. Similarly, p-ERK 1/2 protein levels were suppressed by miR-4529-3p inhibition. Furthermore, downregulation of miR-4529-3p limited tumor growth in vivo. Mechanistically, miR-4259-3p targets RB1. Interestingly, RB1 silencing abrogated the alleviative effects of miR-4529-3p downregulation in RB cells. MiR-4529-3p promotes RB progression by inhibiting RB1 and activating the ERK pathway. This evidence suggests that the miR-4529-3p/RB1 regulatory axis may be a prospective target for RB treatment in clinical settings.
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Affiliation(s)
- Yuan Gao
- Department of Ophthalmology, Wuhan No.1 Hospital, No. 215, Zhongshan Avenue, Qiaokou District, Wuhan, 430022, Hubei, China.
| | - Pei Du
- Department of Ophthalmology, Wuhan No.1 Hospital, No. 215, Zhongshan Avenue, Qiaokou District, Wuhan, 430022, Hubei, China
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2
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Deichaite I, Hopper A, Krockenberger L, Sears TJ, Sutton L, Ray X, Sharabi A, Navon A, Sanghvi P, Carter H, Moiseenko V. Germline genetic biomarkers to stratify patients for personalized radiation treatment. J Transl Med 2022; 20:360. [PMID: 35962345 PMCID: PMC9373374 DOI: 10.1186/s12967-022-03561-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2022] [Accepted: 07/29/2022] [Indexed: 11/10/2022] Open
Abstract
Background Precision medicine incorporating genetic profiling is becoming a standard of care in medical oncology. However, in the field of radiation oncology there is limited use of genetic profiling and the impact of germline genetic biomarkers on radiosensitivity, radioresistance, or patient outcomes after radiation therapy is poorly understood. In HNSCC, the toxicity associated with treatment can cause delays or early cessation which has been associated with worse outcomes. Identifying potential biomarkers which can help predict toxicity, as well as response to treatment, is of significant interest. Methods Patients with HNSCC who received RT and underwent next generation sequencing of somatic tumor samples, transcriptome RNA-seq with matched normal tissue samples were included. Patients were then grouped by propensity towards increased late vs. early toxicity (Group A) and those without (Group B), assessed by CTCAE v5.0. The groups were then analyzed for association of specific germline variants with toxicity and clinical outcomes. Results In this study we analyzed 37 patients for correlation between germline variants and toxicity. We observed that TSC2, HLA-A, TET2, GEN1, NCOR2 and other germline variants were significantly associated with long term toxicities. 34 HNSCC patients treated with curative intent were evaluated for clinical outcomes. Group A had significantly improved overall survival as well as improved rates of locoregional recurrence and metastatic disease. Specific variants associated with improved clinical outcomes included TSC2, FANCD2, and PPP1R15A, while the HLA-A and GEN1 variants were not correlated with survival or recurrence. A group of five HLA-DMA/HLA-DMB variants was only found in Group B and was associated with a higher risk of locoregional recurrence. Conclusions This study indicates that germline genetic biomarkers may have utility in predicting toxicity and outcomes after radiation therapy and deserve further investigation in precision radiation medicine approaches.
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Affiliation(s)
- Ida Deichaite
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA. .,Moores Cancer Center, University of California San Diego, La Jolla, CA, USA.
| | - Austin Hopper
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA
| | - Lena Krockenberger
- Moores Cancer Center, University of California San Diego, La Jolla, CA, USA
| | - Timothy J Sears
- Bioinformatics and Systems Biology Program, University of California San Diego, La Jolla, CA, USA
| | - Leisa Sutton
- Moores Cancer Center, University of California San Diego, La Jolla, CA, USA
| | - Xenia Ray
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA
| | - Andrew Sharabi
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA.,Moores Cancer Center, University of California San Diego, La Jolla, CA, USA
| | - Ami Navon
- Department of Biological Regulation, Weizmann Institute of Science, Rehovot, Israel
| | - Parag Sanghvi
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA
| | - Hannah Carter
- Moores Cancer Center, University of California San Diego, La Jolla, CA, USA.,Division of Medical Genetics, Department of Medicine, University of California San Diego, La Jolla, CA, USA
| | - Vitali Moiseenko
- Department of Radiation Medicine and Applied Sciences, University of California San Diego, La Jolla, CA, USA
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Nickoloff JA, Taylor L, Sharma N, Kato TA. Exploiting DNA repair pathways for tumor sensitization, mitigation of resistance, and normal tissue protection in radiotherapy. CANCER DRUG RESISTANCE (ALHAMBRA, CALIF.) 2021; 4:244-263. [PMID: 34337349 PMCID: PMC8323830 DOI: 10.20517/cdr.2020.89] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
Abstract
More than half of cancer patients are treated with radiotherapy, which kills tumor cells by directly and indirectly inducing DNA damage, including cytotoxic DNA double-strand breaks (DSBs). Tumor cells respond to these threats by activating a complex signaling network termed the DNA damage response (DDR). The DDR arrests the cell cycle, upregulates DNA repair, and triggers apoptosis when damage is excessive. The DDR signaling and DNA repair pathways are fertile terrain for therapeutic intervention. This review highlights strategies to improve therapeutic gain by targeting DDR and DNA repair pathways to radiosensitize tumor cells, overcome intrinsic and acquired tumor radioresistance, and protect normal tissue. Many biological and environmental factors determine tumor and normal cell responses to ionizing radiation and genotoxic chemotherapeutics. These include cell type and cell cycle phase distribution; tissue/tumor microenvironment and oxygen levels; DNA damage load and quality; DNA repair capacity; and susceptibility to apoptosis or other active or passive cell death pathways. We provide an overview of radiobiological parameters associated with X-ray, proton, and carbon ion radiotherapy; DNA repair and DNA damage signaling pathways; and other factors that regulate tumor and normal cell responses to radiation. We then focus on recent studies exploiting DSB repair pathways to enhance radiotherapy therapeutic gain.
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Affiliation(s)
- Jac A. Nickoloff
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
- Correspondence Address: Dr. Jac A. Nickoloff, Department of Environmental and Radiological Health Sciences, Colorado State University, 1681 Campus Delivery, Ft. Collins, CO 80523-1681, USA. E-mail:
| | - Lynn Taylor
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Neelam Sharma
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
| | - Takamitsu A. Kato
- Department of Environmental and Radiological Health Sciences, Colorado State University, Ft. Collins, CO 80523, USA
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Bergom C, West CM, Higginson DS, Abazeed ME, Arun B, Bentzen SM, Bernstein JL, Evans JD, Gerber NK, Kerns SL, Keen J, Litton JK, Reiner AS, Riaz N, Rosenstein BS, Sawakuchi GO, Shaitelman SF, Powell SN, Woodward WA. The Implications of Genetic Testing on Radiation Therapy Decisions: A Guide for Radiation Oncologists. Int J Radiat Oncol Biol Phys 2019; 105:698-712. [PMID: 31381960 DOI: 10.1016/j.ijrobp.2019.07.026] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Revised: 06/21/2019] [Accepted: 07/08/2019] [Indexed: 02/06/2023]
Abstract
The advent of affordable and rapid next-generation DNA sequencing technology, along with the US Supreme Court ruling invalidating gene patents, has led to a deluge of germline and tumor genetic variant tests that are being rapidly incorporated into clinical cancer decision-making. A major concern for clinicians is whether the presence of germline mutations may increase the risk of radiation toxicity or secondary malignancies. Because scarce clinical data exist to inform decisions at this time, the American Society for Radiation Oncology convened a group of radiation science experts and clinicians to summarize potential issues, review relevant data, and provide guidance for adult patients and their care teams regarding the impact, if any, that genetic testing should have on radiation therapy recommendations. During the American Society for Radiation Oncology workshop, several main points emerged, which are discussed in this manuscript: (1) variants of uncertain significance should be considered nondeleterious until functional genomic data emerge to demonstrate otherwise; (2) possession of germline alterations in a single copy of a gene critical for radiation damage responses does not necessarily equate to increased risk of radiation-induced toxicity; (3) deleterious ataxia-telangiesctasia gene mutations may modestly increase second cancer risk after radiation therapy, and thus follow-up for these patients after indicated radiation therapy should include second cancer screening; (4) conveying to patients the difference between relative and absolute risk is critical to decision-making; and (5) more work is needed to assess the impact of tumor somatic alterations on the probability of response to radiation therapy and the potential for individualization of radiation doses. Data on radiosensitivity related to specific genetic mutations is also briefly discussed.
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Affiliation(s)
- Carmen Bergom
- Department of Radiation Oncology, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Catharine M West
- Division of Cancer Sciences, National Institute for Health Research Manchester Biomedical Research Centre, University of Manchester, Christie National Health Service Foundation Trust Hospital, Manchester, UK
| | - Daniel S Higginson
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Mohamed E Abazeed
- Department of Radiation Oncology, Cleveland Clinic, Cleveland, Ohio; Department of Translational Hematology Oncology Research, Cleveland Clinic, Cleveland, Ohio
| | - Banu Arun
- Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Soren M Bentzen
- Department of Epidemiology and Public Health, University of Maryland School of Medicine, Baltimore, Maryland
| | - Jonine L Bernstein
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Jaden D Evans
- Department of Radiation Oncology, Mayo Clinic, Rochester, Minnesota; Department of Radiation Oncology and Precision Genomics, Intermountain Healthcare, Ogden, Utah
| | - Naamit K Gerber
- Department of Radiation Oncology, New York University Langone Health, New York, New York
| | - Sarah L Kerns
- Department of Radiation Oncology, University of Rochester, Rochester, New York
| | - Judy Keen
- Scientific Affairs, American Society for Radiation Oncology, Arlington, Virginia
| | - Jennifer K Litton
- Department of Breast Medical Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Anne S Reiner
- Department of Epidemiology and Biostatistics, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Nadeem Riaz
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Barry S Rosenstein
- Department of Radiation Oncology, Icahn School of Medicine at Mount Sinai, New York, New York; Department of Genetics and Genomic Sciences, Icahn School of Medicine at Mount Sinai, New York, New York
| | - Gabriel O Sawakuchi
- Department of Radiation Physics The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Simona F Shaitelman
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas
| | - Simon N Powell
- Department of Radiation Oncology, Memorial Sloan Kettering Cancer Center, New York, New York
| | - Wendy A Woodward
- Department of Radiation Oncology, The University of Texas MD Anderson Cancer Center, Houston, Texas.
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Low EK, Brudvik E, Kuhlman B, Wilson PF, Almeida-Porada G, Porada CD. Microgravity Impairs DNA Damage Repair in Human Hematopoietic Stem/Progenitor Cells and Inhibits Their Differentiation into Dendritic Cells. Stem Cells Dev 2018; 27:1257-1267. [DOI: 10.1089/scd.2018.0052] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Erica K. Low
- Banner Good Samaritan Medical Center, Phoenix, Arizona
| | - Egil Brudvik
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Bradford Kuhlman
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Paul F. Wilson
- Department of Radiation Oncology, University of California Davis Comprehensive Cancer Center, Sacramento, California
| | - Graça Almeida-Porada
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina
| | - Christopher D. Porada
- Wake Forest Institute for Regenerative Medicine, Wake Forest School of Medicine, Winston Salem, North Carolina
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Wilson PF. Magnification of Inter-individual Variation in Biological Responses After Low Doses and Dose-Rates of Ionizing Radiation. HEALTH PHYSICS 2016; 110:296-298. [PMID: 26808888 DOI: 10.1097/hp.0000000000000453] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Biological responses of human cells and tissues to ionizing radiation (IR) are strongly influenced by dose and dose-rate. Unlike the robust activation of cellular DNA damage responses (DDR) seen after high IR doses, the efficiency of activation of DNA damage repair and signaling pathways after much lower doses and dose-rates varies appreciably among different individuals. Genomic and functional assays measuring low dose and dose-rate IR responses repeatedly show increased inter-individual variability when cells and tissues experience DNA damage levels comparable to those experienced endogenously (due to aerobic metabolism, diet, lifestyle, etc). Complicating matters for risk assessment are recent observations of dose-response non-linearity (hyper-linearity) in the low dose range. With both physical and biological factors strongly influencing individual responses to IR at low doses and dose-rates, further radiobiological research is required to assist regulatory agencies in determining appropriate radiological protection standards for such exposures.
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Affiliation(s)
- Paul F Wilson
- *Biological, Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, NY 11973
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7
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Yang Y, Tian S, Brown B, Chen P, Hu H, Xia L, Zhang J, Cai X, Chen Z, Pan X, Ge J, Yu K, Zhuang J. The Rb1 gene inhibits the viability of retinoblastoma cells by regulating homologous recombination. Int J Mol Med 2013; 32:137-43. [PMID: 23670186 DOI: 10.3892/ijmm.2013.1374] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2013] [Accepted: 04/09/2013] [Indexed: 11/06/2022] Open
Abstract
Retinoblastoma is a childhood ocular tumor caused by the inactivation of both alleles of the retinoblastoma gene (Rb1). Without Rb1 gene function, chromosomal aberrations are observed in retinoblastoma cells. The instability of the genome is closely associated with the repair of DNA double-strand breaks (DSBs). However, the precise molecular mechanism of action of Rb1 in DNA DSB repair remains unclear. Thus, in this study, we aimed to investigate whether the Rb1 gene affects DNA stability by assaying DNA DSB repair and also whether it regulates the proliferation of retinoblastoma cells. Rb1 immunofluorescence and RT-PCR were performed, demonstrating that the Rb1 gene is silenced in SO-Rb50 retinoblastoma cells, and the karyotype analysis of SO-Rb50 cells indicated that the loss of Rb1 function led to genomic instability; both numerical and structural chromosomal aberrations were observed in our study. In addition, the DNA DSB repair efficiency of the SO-Rb50 cells was measured by γ-H2AX immunofluorescence, a commonly used in situ marker of DNA DSBs, following exposure to ionizing radiation (IR) (2.5 and 5.0 Gy). We found that the DNA repair efficiency was significantly increased following IR-induced damage (P<0.01). However, there was no significant difference in DNA repair efficiency between the cells expressing exogenous Rb1 and the control (P>0.05). The assay for the screening of the effect of Rb1 on the sub-pathway of DNA DSB repair, non-homologous end joining (NHEJ) and homologous recombination (HR), indicated that Rb1 did not affect NHEJ activity, although it significantly promoted the HR pathway (HR levels increased by 2.46-fold) compared with the control (P<0.01). Furthermore, we found that the cell viability of the SO-Rb50 cells transfected with exogenous Rb1 was significantly inhibited (P<0.01) and cell cycle assay indicated that exogenous Rb1 induced S phase arrest (P<0.001) which also inhibited the proliferation of retinoblastoma cells (SO-Rb50) in vitro. Therefore, this study provides new insight into the mechanisms of action of the Rb1 gene in regulating the proliferation of retinoblastoma cells.
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Affiliation(s)
- Ying Yang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou 510060, P.R. China
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8
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Genetic predisposition to radiation-related cancer and potential implications for risk assessment. Ann ICRP 2012; 41:108-16. [PMID: 23089009 DOI: 10.1016/j.icrp.2012.06.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Several lines of evidence suggest that risk estimates for cancer associated with radiation exposure incorporate individuals who are more and less inherently susceptible to the carcinogenic effects of radiation, and the technology to further evaluate this issue is now available. For example, genome-wide association scan studies could be undertaken to address, at least in part, the direction of causality in the observations of differential sensitivity to radiomimetic agents in cancer cases compared with normal individuals, thereby building on previous observations that sensitivity to these agents is higher in apparently normal individuals carrying gene mutations in NBS and ATM. Direct studies of risk of second cancers in relation to radiation are underway, and some results have been reported (e.g. for the PRDM1 gene as related to sensitivity to radiation-related cancers after treatment for Hodgkin's lymphoma). It is important to understand the risk synergies between variants affecting associations with various cancers defining susceptibility in unexposed populations and the excess risk in populations therapeutically or occupationally exposed to radiation for the purpose of risk protection, especially as additional baseline risk variants are discovered in increasingly large-scale analyses. While there are studies that are beginning to address these questions, there have been no compelling new discoveries, to date, to indicate that predisposition information should be included in risk assessment. The conclusions in ICRP Publications 79 and 103 appear relevant today.
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9
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Salama S, Diaz-Arrastia C, Patel D, Botting S, Hatch S. 2-Methoxyestradiol, an Endogenous Estrogen Metabolite, Sensitizes Radioresistant MCF-7/FIR Breast Cancer Cells Through Multiple Mechanisms. Int J Radiat Oncol Biol Phys 2011; 80:231-9. [DOI: 10.1016/j.ijrobp.2010.10.080] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2010] [Revised: 10/12/2010] [Accepted: 10/13/2010] [Indexed: 10/18/2022]
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Yun J, Li Y, Xu CT, Pan BR. Epidemiology and Rb1 gene of retinoblastoma. Int J Ophthalmol 2011; 4:103-9. [PMID: 22553621 DOI: 10.3980/j.issn.2222-3959.2011.01.24] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 01/20/2010] [Indexed: 11/02/2022] Open
Abstract
Retinoblastoma (Rb) is the most common eye cancer in children and it can be inherited. Rb is quite rare and originators from the neural retina with a significant genetic component in etiology, which occurs in approximately 1 in every 20 0000 births. In children with the heritable genetic form of Rb, there is a mutation on chromosome 13, called the retinoblastoma 1 (Rb1) gene. Early diagnosis and intervention is critical to the successful treatment of the Rb. The Rb1 gene is the first cloned tumor suppressor gene. As a negative regulator of the cell cycle, Rb1 gene could maintain a balance between cell growth and development through binding to transcription factors and regulating the expression of genes involved in cell proliferation and differentiation. Thus, it is involved in cell cycle, cell senescence, growth arrest, apoptosis and differentiation. We summarized the recent advances on the epidemiology and Rb1 gene of Rb in this review.
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Affiliation(s)
- Jun Yun
- Department of General Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an 710032, Shaanxi Province, China
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11
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Wilson DM, Kim D, Berquist BR, Sigurdson AJ. Variation in base excision repair capacity. Mutat Res 2010; 711:100-12. [PMID: 21167187 DOI: 10.1016/j.mrfmmm.2010.12.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Revised: 11/29/2010] [Accepted: 12/07/2010] [Indexed: 01/20/2023]
Abstract
The major DNA repair pathway for coping with spontaneous forms of DNA damage, such as natural hydrolytic products or oxidative lesions, is base excision repair (BER). In particular, BER processes mutagenic and cytotoxic DNA lesions such as non-bulky base modifications, abasic sites, and a range of chemically distinct single-strand breaks. Defects in BER have been linked to cancer predisposition, neurodegenerative disorders, and immunodeficiency. Recent data indicate a large degree of sequence variability in DNA repair genes and several studies have associated BER gene polymorphisms with disease risk, including cancer of several sites. The intent of this review is to describe the range of BER capacity among individuals and the functional consequences of BER genetic variants. We also discuss studies that associate BER deficiency with disease risk and the current state of BER capacity measurement assays.
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Affiliation(s)
- David M Wilson
- Laboratory of Molecular Gerontology, National Institute on Aging, National Institutes of Health, Baltimore, MD 21224, United States.
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12
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Wilson PF, Hinz JM, Urbin SS, Nham PB, Thompson LH. Influence of homologous recombinational repair on cell survival and chromosomal aberration induction during the cell cycle in gamma-irradiated CHO cells. DNA Repair (Amst) 2010; 9:737-44. [PMID: 20434408 DOI: 10.1016/j.dnarep.2010.03.009] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2010] [Revised: 03/23/2010] [Accepted: 03/26/2010] [Indexed: 11/29/2022]
Abstract
The repair of DNA double-strand breaks (DSBs) by homologous recombinational repair (HRR) underlies the high radioresistance and low mutability observed in S-phase mammalian cells. To evaluate the contributions of HRR and non-homologous end-joining (NHEJ) to overall DSB repair capacity throughout the cell cycle after gamma-irradiation, we compared HRR-deficient RAD51D-knockout 51D1 to CgRAD51D-complemented 51D1 (51D1.3) CHO cells for survival and chromosomal aberrations (CAs). Asynchronous cultures were irradiated with 150 or 300cGy and separated by cell size using centrifugal elutriation. Cell survival of each synchronous fraction ( approximately 20 fractions total from early G1 to late G2/M) was measured by colony formation. 51D1.3 cells were most resistant in S, while 51D1 cells were most resistant in early G1 (with survival and chromosome-type CA levels similar to 51D1.3) and became progressively more sensitive throughout S and G2. Both cell lines experienced significantly reduced survival from late S into G2. Metaphases were collected from every third elutriation fraction at the first post-irradiation mitosis and scored for CAs. 51D1 cells irradiated in S and G2 had approximately 2-fold higher chromatid-type CAs and a remarkable approximately 25-fold higher level of complex chromatid-type exchanges compared to 51D1.3 cells. Complex exchanges in 51D1.3 cells were only observed in G2. These results show an essential role for HRR in preventing gross chromosomal rearrangements in proliferating cells and, with our previous report of reduced survival of G2-phase NHEJ-deficient prkdc CHO cells [Hinz et al., DNA Repair 4, 782-792, 2005], imply reduced activity/efficiency of both HRR and NHEJ as cells transition from S to G2.
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Affiliation(s)
- Paul F Wilson
- Biosciences and Biotechnology Division, Lawrence Livermore National Laboratory, Livermore, CA 94551-0808, USA
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